In many areas of the world, population density is such that it is impossible to provide educational programs to prospective students in sparsely populated areas because of the small class size. Attempts to provide such areas with special educational programs have failed because there are not enough qualified instructors to man the small, scattered sites and if an adequate number of instructors are available, the per-student cost is prohibitive.
With the advent of television, it has become possible for a single instructor to reach a plurality of small, remote classes. In such systems, a teacher presents a lesson, either live or via a video tape record. The program is transmitted to schools all over the area, but it suffers a significant disadvantage because the students are placed in a passive role. A student in a passive role has a very limited concentration period before his mind starts to wander. Thus educational television with a student in a passive role cannot meet the real demands of the educational system.
Attempts have been made, in educational TV, to place a student in a more active role. One such attempt is presented in U.S. Pat. No. 3,606,688 on "Method And Apparatus For Teaching A Multiplicity Of Students" issued to Zawels et al on Sept. 21, 1971. In this system, each remote classroom has a TV receiver and a means to respond to student answers invoked by questions presented by the program. However, the system has no way of providing true communication between a student and the lecturer and only a limited number of expected student responses can be coped with.
Other student response systems have been utilized wherein a telephone communication link is provided between remote classrooms and the instructor. In this type of system, the instructor is handicapped because of his inability or difficulty in identifying the student responding and the expense of the complex land line communication system is prohibitive.
Two-way television systems are available to solve this educational TV dilemma, however their cost has been prohibitively expensive due to the large amount of equipment required to link a plurality of educational sites. One such system which could be used is presented in U.S. Pat. No. 2,907,874 on "Microwave Communication System" issued to R. Halvorson on Oct. 6, 1958. This system utilizes a plurality of repeater stations, each of which have multiplexing equipment that could conceivably be used to tie a classroom receiver-transmitter into the link. Systems such as this are costly and the initial installation expense coupled with the maintenance requirements far exceeds the expenditure of providing individual instructors at each sub-station. Therefore, television microwave communication systems including a plurality of sub-stations having multiplex equipment provides a workable solution to the educational TV dilemma but financially the approach is not practical.